Coffee is a beverage that has a taste and aroma which is more desirable when it is fresh than when it is older and "stale." This is because the compounds which contribute flavor to the coffee are organic in nature and the flavor is the most desirable immediately after the coffee is brewed because the compounds which impart the flavor have not degraded. Over a period of time the organic compounds of the coffee oxidize by combining with oxygen in the water from which the coffee is brewed and the oxidation results in the degradation of the coffee and the loss of the desirable flavor.
There are numerous brands and types of coffees available, and coffee can be brewed such that it is "strong " or "weak " or to any intermediate strength. Individuals who regularly drink coffee desire that the brew have a "strength " and level of "freshness " which is satisfactory to their own palate, and therefore the strength and the freshness of coffee are critical variables to connoisseurs of coffee.
One who makes a pot of coffee may grind or purchase his choices of coffee grinds and place those grinds within the hopper of a coffee maker. Hot water is either percolated through the grinds or it may flow from a reservoir above the hopper through the grinds to a removable coffeepot below the hopper. The degradation of the coffee commences as the pot is filling with coffee and proceeds at a rate that may vary depending on the type of coffee and the degree of the grinding.
In our previous U.S. Pat. No. 5,724,882, we disclosed a coffee maker having an optical feedback system in which a red light from an LED was directed through a transparent coffee pot and the intensity of the light passing through the liquid was monitored to make a brew having a predetermined concentration. U.S. Pat. No. 5,724,882, therefore, disclosed a method and apparatus for brewing coffee to a predetermined strength. Coffee from a coffee maker in accordance with our prior invention will nonetheless become stale over time, and a connoisseur of coffee employing such a coffee maker could not ascertain whether the coffee has become too stale for his palate without tasting it. It would be desirable, therefore, to provide a coffee maker which would brew coffee at a desirable concentration or strength and which would also provide a readout of the freshness of the brew remaining in the pot.